The present invention is related to aircraft heat exchangers, and in particular to a system and method for detecting contamination and blockage in heat exchangers to prevent ram air fan surge.
Aircraft often include environmental control systems (ECS) that provide cool, pressurized air for the aircraft. Each ECS may also include one or more ram air fans that draw air through heat exchangers to provide air-to-air cooling for a bleed air flow, for example. Contamination from the ambient air may increase the pressure drop across the heat exchangers, reducing the air flow through the fan. Significant heat exchanger contamination can reduce the air flow enough that the ram air fan may operate in an unstable operating mode, which may lead to mechanical damage or failure of the fan and/or other components of an air cycle machine coupled to the fan.